A full duplex system (see FIG. 7) in which an operating node and a standby node are operated completely independently has been conventionally used by companies, or the like, for the purpose of maintaining the absolutely stable operation of a database. The full duplex system maintains the standby node in a startup state, so that the full duplex system achieves data synchronization between a database in the operating node and a database in the standby node by using an update difference log, and performs a switching process between the operating node and the standby node on the second time scale.
Technologies for quickly performing a switching process to switch a standby node to a new operating node if a problem occurs in an operating node of a system, such as a full duplex system, has already been disclosed (see, for example, Japanese Laid-open Patent Publication No. 2004-348701). Generally, if a problem is detected in an operating node of a full duplex system, a switching process is performed to switch a standby node to a new operating node after processing (for example, transaction processing) performed by the operating node is stopped, so that the processing performed by the operating node is taken over by the new operating node.
In the above conventional technology, there are problems in that it is difficult for a user to select a transaction to be stopped from transactions being processed by the operating node and, because the conventional technology usually employs a method for switching a standby node to a new operating node after all transactions being processed by the operating node have been completed, the standby node may not be quickly switched to the new operating node.
For example, if a problem is detected in some operating nodes of a full duplex system (a full duplex system having a configuration that allows for expandability) that includes a plurality of nodes, not only the operating nodes but also an AP (application) server need to be concurrently switched over or, because consistency of information managed by a DBMS (database management system) needs to be ensured, each of standby nodes that are pairs of all operating nodes, including properly operating nodes, in the full duplex system needs to be switched to a new operating node (see FIG. 8). Because it is necessary to stop transactions being processed in all operating nodes before a switching process is performed, there is a problem in that sometimes each of the standby nodes that are pairs of all operating nodes, including the properly operating nodes, in the full duplex system may not be switched quickly to a new operating node. Although the transaction processing is usually stopped by using a method of stopping an instance of a DBMS in a conventional technology, because it is necessary to wait for completion of all termination processes, such as a rollback process or an abnormality recovery process, in such a method, the method may not be used if a switching process needs to be performed quickly.